Membrane material having immiscible polymers for use in optical fiber cable structures

Abstract

Provided are embodiments of an extruded membrane material. The extruded membrane material includes a first thermoplastic polymer and a second thermoplastic polymer. The first thermoplastic polymer and the second thermoplastic polymer are immiscible. The first thermoplastic polymer forms a first phase oriented along an extrusion direction, and the second thermoplastic polymer forms a second phase oriented along the extrusion direction. The first phase is co-continuous with the second phase. Further, the extruded membrane material has a tensile yield strength of at least 10 MPa along the extrusion direction and a peel strength of 4 N or less transverse to the extrusion direction.

What is claimed is: 
     
         1 . A subunit, comprising:
 a plurality of optical fibers; and   a membrane surrounding the plurality of optical fibers, the membrane formed of an extruded material comprising:
 a first thermoplastic polymer; and 
 a second thermoplastic polymer; 
 wherein the first thermoplastic polymer and the second thermoplastic polymer are immiscible; 
 wherein the first thermoplastic polymer forms a first phase oriented along an extrusion direction and the second thermoplastic polymer forms a second phase oriented along the extrusion direction, the first phase being co-continuous with the second phase; 
 wherein the extruded membrane material comprises a tensile yield strength of at least 10 MPa along the extrusion direction and a peel strength of 4 N or less transverse to the extrusion direction. 
   
     
     
         2 . The subunit of  claim 1 , wherein the first thermoplastic polymer is a polyolefin. 
     
     
         3 . The subunit of  claim 2 , wherein the polyolefin is selected from a group consisting of polyethylene, a polypropylene, a polyolefin-based elastomer, and combinations thereof. 
     
     
         4 . The subunit of  claim 2 , wherein the polyolefin is a polyethylene or a polypropylene. 
     
     
         5 . The subunit of  claim 4 , wherein the second thermoplastic polymer is a technical thermoplastic. 
     
     
         6 . The subunit of  claim 5 , wherein the technical thermoplastic is selected from a group consisting of a polyester, a polyether, a polyamide, a polyacetal, a polysulfone, a polyimide, a polyketone, and combinations thereof. 
     
     
         7 . The subunit of  claim 5 , wherein the extruded material comprises from 25 wt % to 85 wt % of the polyolefin and from 15 wt % to 75 wt % of the technical thermoplastic. 
     
     
         8 . The subunit of  claim 1 , wherein the first thermoplastic polymer and the second thermoplastic polymer are selected from a group consisting of a polyolefin, a polyvinylchloride, a polystyrene, an acrylonitrile butadiene styrene, a styrene-acrylonitrile, a styrene-ethylene-butylene-styrene, and combinations thereof. 
     
     
         9 . The subunit of  claim 1 , wherein the extruded material further comprises a third thermoplastic polymer. 
     
     
         10 . The subunit of  claim 9 , wherein the third thermoplastic polymer comprises a technical thermoplastic. 
     
     
         11 . The subunit of  claim 10 , comprising from 5 wt % to 95 wt % of the first thermoplastic polymer, from 5 wt % to 93 wt % of the second thermoplastic polymer, and from 2 wt % to 10 wt % of the technical thermoplastic. 
     
     
         12 . The subunit of  claim 1 , wherein the membrane has a thickness of 100 μm or less. 
     
     
         13 . An optical fiber cable, comprising:
 a cable jacket comprising an inner surface and an outer surface, the inner surface defining a central bore extending along a longitudinal axis of the optical fiber cable and the outer surface defining an outermost surface of the optical fiber cable;   a plurality of subunits according to  claim 1  disposed within the central bore;   wherein the outer surface of the cable jacket defines a cross-sectional area perpendicular to the longitudinal axis and wherein the optical fiber cable comprises a fiber density of at least 7.5 fibers/mm 2  as measured at the cross-sectional area.   
     
     
         14 . A method of forming an optical fiber subunit, comprising:
 blending a first thermoplastic polymer with a second thermoplastic polymer, the first thermoplastic polymer being immiscible with the second thermoplastic polymer;   extruding the first thermoplastic polymer and the second thermoplastic polymer together to form a membrane that surrounds a plurality of optical fibers, wherein the first thermoplastic polymer forms a first phase oriented along an extrusion direction and the second thermoplastic polymer forms a second phase oriented along the extrusion direction, the first phase being co-continuous with the second phase;   wherein the membrane has a tensile yield strength of at least 10 MPa along the extrusion direction and a peel strength of 4 N or less transverse to the extrusion direction.   
     
     
         15 . The method of  claim 14 , wherein blending further comprises blending the first thermoplastic polymer and the second thermoplastic polymer with a coupling agent. 
     
     
         16 . The method of  claim 15 , wherein the coupling agent comprises either the first thermoplastic polymer or the second thermoplastic polymer functionalized with a functional group selected from a group consisting of maleic anhydride, silane, epoxy, acrylate, amine, hydroxyl, melamine, zirconate, titanate, polyol, or ester. 
     
     
         17 . The method of  claim 15 , wherein the membrane material comprises up to 15 wt % of the coupling agent. 
     
     
         18 . The method of  claim 15 , wherein the first thermoplastic polymer is a first polyolefin. 
     
     
         19 . The method of  claim 18 , wherein the second thermoplastic polymer is a technical thermoplastic. 
     
     
         20 . The method of  claim 18 , wherein the second thermoplastic polymer is a second polyolefin different from the first polyolefin.